Defrosting system



May 14, 1935.

W. R. KITZMILLER DEFROSTING SYSTEM Filed Sept. 26, 1952 ZMQLUZS 2SheetsSheet 1 PEP-1+ 45 William Rifitgmiiler I May 14,1935. v w. R.KKTZMILLER I 2,001,028

DEFROSTING SYSTEM Filed Sept. 26, 1932 2 Shee ts-Shee 2 Patented May 14,l 935 NT OFFl aromas fnmos'rmo SYSTJEIW William R. Kitzmiller,Waynesboro, Pa, assignor to Frick Company, Waynesboro, Pa, a corporationof Pennsylvania.

Application September 26, 1932, Serial No. 634,947

9Claims.

This invention relates to defrosting of coolers and while it may beadapted for any uses for which suited it is designed particularly with aview to its use in the cooling of air in a room or chamber. Due to thepresence of moisture in a room or chamber a deposit of frost or iceforms on the evaporator or other cooler through which the air beingcooled is circulated. This accumulation of frost, greatly retardscooling of the air, since frost and ice are poor conductors of heat.Moreover the accumulation of frost may impede the passage of air throughthe cooler, and thereby greatly reduce the efficiency of the device.

My invention therefore relates to improvements in means forautomatically defrosting a cooler when the frost has accumulated to anobjectionable degree.

The system'is an improvement over that'shown in my copending applicationSerial No. 561,800,

filed September 8, 1931 for Defrosting systems.

Referring to the accompanying drawings, which are made a part hereof andon which similar reference characters indicate similar parts, Figure 1is a view in elevation of the preferred form of the invention withcertain parts shown diagrammatically,

Figure 2, a view in elevation partly diagram- 1niiatic of a slightlydifferent form of the inven- Figure 3, a diagrammatic lay-out of aninterlocked system which may be used with either of the two forms justdescribed, and

Figure 4, a view in elevation partly diagram-v matic o1v a slightlydiflerent form of the invention.

In the drawings numeral l0 indicates a motor which is operated by threephase current from lines ll, l2 and I3. The wire I3 is coiled about asolenoid I to provide a means for operating a switch 2| for a purposewhich will later appear. The motor l0 operates a fan l8 for forcing airto be cooled through the evaporator or other cooler IS. The fan may beoperated so as to force the air through the evaporator or 'to draw itthrough the evaporator as desired. The refrigerant which may be a coldbrine or-a volatile refrigerant is' circulated through the evaporator orcooler and is drawn out. through a valve l1 and passes to the suction ofa compressor or pump not shown. Refrigerant to the evaporator passesthrough a valve 20. During normal operation the parts will be in theposition shown in Figure ,1 in which the valves 20 and I! will be openso that refrigerant will freely circulate through the evaporator and thefan will operate to circulate air through the evaporator to cool theair. Under certain conditions the valve 20 may be omitted and any othersuitable means provided for expansion or feeding of fluid to the cooler.This valve may be of the float type, automatic expansion valve, etc.When the evaporator has become coated with frost so as to impede thepassage of air through the evaporator the load on the motor It! will beaffected and this change in load will energize coil M of switch 2 l,thereby opening the circuit from line H to line l2 through conductors 22and 23 and solenoids 24 and 25, and close the circuit through conductors22 and and solenoids 28 and 29. This will de-energize solenoids 24 and25 to close the valves l1 and 29. Valves 26 and 27 are arranged to openwhen solenoids 28 and 29 are energized by closing the circuit 30 and 3|with lines l2 and I 3. When the valves 26 and 21 are opened warm fluidwill be circulated through the evaporator l5. The evaporator willtherefore be quickly defrosted. As soon as the frost has been re' movedfrom the evaporator coils the switch 2| will opencircuit 22, 30 closingcircuit through 22, 23, and this in turn will open valve I1 and valve 20and close valves 26 and 21 so that the hot fluid will be cut off fromthe evaporator and the cold refrigerant will again circulate through thecoils. The'defrostlng of the coils will require only a short time sothat the temperature in the room will not be seriously affected duringthefew moments required to defrost the coils. The system therefore willoperate automatically to maintain the coils relatively free of frost. Ifdesired under certain-conditions valve 2! may beomitted in which casethe defrosting fluid can pass on to the compressor or pump through valve|1. It will be possible-in some cases to operate without valve 20 andoperate with afloat control or other means of expansion in place ofvalve 20. These combinations will depend on the work being done andtemperatures required. When operating with a direct expansionrefrigerant, it will often be possible to simply use valve I1 and valve26 for the defrosting cycle. The refrigerant will be expanded throughvalve 20 which may be of the float type or as explained above. When theunit I5 has become heavily frosted, electrical device 2| will beoperated to break the circuit through conductor 23 and close the circuitthrough conductor 30, thus closing the valve l1 and closing circuitthrough lines I3, 30 and 3| thus opening valve 26.

The cut-out switch I9 is provided as a further feature of safety and isoperated in response to great temperature or pressure changes in the hotfluid which passes through the pipe I8 to the evaporator. When thisfluid is too warm or pressure too high the switch H! which is a pressureor thermostat switch will open and break the circuit through line 3|.This will permit valve 26 to close. This safety feature also insurespartial control of defrosting time since it would control the flow ofwarm fluid in some cases.

The arrangement shown in Figure 2 is similar to that shown in Figure 1except that there is provided a time lag switch at 33. The time device33 tends to hold the valve 34 closed a little beyond the regulardefrosting period to insure the complete removal of snow and ice fromthe evaporator coils. In other words the electrical device 33 actssimply as a time lag in the opening of valve 34 to place the unit backinto normal operation.

It may be necessary to provide means for insuring positive operation ofthe switch 2| in the event the electrical device should not hold theproper contact.

An interlocked system shown diagrammatically in Figure 3 provides foroperating the switch 2! so that operation will be insured regardless ofany interfering circumstances. In this interlocked system the wire 35 isconnected in series through a coil 38 to operate the switch 39. Duringdefrosting operation of the cooling system the switch 39 will be in theposition shown in Figure 3 and the circuit will be closed from line 36through wires 40, 4!, switch 42 and wire 43 to the wire 35. This willenergize solenoid 44 to open the valve 45 which controls the hot fluidto the evaporator. At the same time solenoid 45 will be de-energized sothat the suction valve 41 from the evaporator will be closed. When theload on the motor l varies from a given standard due to loss of frost onthe evaporator the switch 39 will be moved up to close circuit acrosslines 48 and 49.

The coil 50 will first be energized through lines 40, 52, 4B and 49.This will raise switch 42 to close circuit from line 40 through line 53to 43. This will energize solenoid 46 and open valve 41 to startevaporation of refrigerant, From the description given it will beapparent that the device may be arranged to operate within anypredetermined load changes on the motor which operates the fan whichchange in load is due to an impeding of the passage of air through theevaporator coils.

The wiring hook-up illustrated in Figure 3 is generally known as alock-up system and employs lock-up relays containing proper resistancesto eliminate short circuits. This wiring can be used in various ways tosecure practically the same results and may or may not employ thelock-up system.

The arrangement shown in Figure 4 is practically the same as thoseillustrated in Figures 1 and 2 except that there is provided a timeswitch 54 to operate the defrosting cycle rather than the electricaldevice 55. The relay or electrical device 55 will operate according tothe frost on the cooler. Whenever the frost has built up to anobjectionable point, the electrical device 55 will operate the timedevice 54 which will carry out the defrosting cycle and at the same timestart and stop the fan 56, if desired, through an automatic starter 51.This would be necessary in rooms below freezing since the fan would drawfreezing air over the melting frost and retard,defrosting. The wiringhook-up will depend on the application and type of instrument employed.However, the connections 59 and 60 will be made ahead of the automaticstarter 51 so that current is available to operate the timing devicewhen the fan 56 is shut down.

It will be obvious to those skilled in the art that various changes maybe made in my device without departing from the spirit of the inventionand therefore I do not limit myself to what is shown in the drawings anddescribed in the specification, but only as indicated by the appendedclaims.

Having thus fully described my said invention, what I claim as new anddesire to secure by Letters Patent, is:

1. A device for defrosting a cooler comprising means for circulatingrefrigerant through the cooler, a fan adapted to circulate air over thecooler, a motor for operating said fan, the load on said motor varyingas a result of the increase in the pressure head in the cooler when thecooler becomes heavily coated with frost, and means controlled byvariation in the load on said motor for stopping circulation ofrefrigerant through the cooler and for causing the circulation of a warmfluid therethrough to hasten defrosting of the evaporator, substantiallyas set forth.

2. In a fluid cooling system of the kind described having an evaporator,valve means for controlling the flow of refrigerant through theevaporator, means for circulating the medium to be cooled through theevaporator, a motor for operating said means, means for controlling thesaid valve means in response to variations in the load on said motor dueto impedance of the fluid being cooled due to a frosted condition of theevaporator, and means automatically operated upon closing of said valvemeans for circulating a warm fluid through the refrigerator to hastenthe defrosting of the refrigerator when the flow of refrigerant has beenstopped, substantially as set forth.

3. In a fluid cooling system of the kind described having a cooler,valve means for controlling the flow 'of refrigerant through the cooler,means for circulating the medium to be cooled through the cooler, amotor for operating said means, means for controlling the said valvemeans in response to variations in the load on said motor due toimpedance of the fluid being cooled due to a frosted condition of theevaporator, means for circulating a warm fluid through the cooler tohasten the defrosting of the refrigerator when the flow of refrigeranthas been stopped, and a time delay device for delaying reopening of therefrigerant control valve means for a short time after the load on themotor has returned to normal thereby insuring a complete defrosting ofthe cooler before the resumption of circulation of refrigerant fluidthrough the evaporator, substantially as set forth.

4. In a device of the kind described, a cooler having refrigerant linesconnected thereto and valves for controlling the flow of refrigerantthrough said lines, a separate line also connected with the coolerhaving valves for controlling the flow of a warm fluid therethrough,means for circulating the medium to be cooled into contact with thecooler, a motor for operating said circulating means, means forcontrolling said switch subject to load on the motor due to a frostedcondition of the cooler, said switch being in control of the valves forcirculating refrigerant and for circulating a warming fluidthroughthecooler, the

warm fluid being circulated to remove the frost after the evaporatorbecomes objectionably coated with'frost, substantially as set forth.

5. In a device of the kind described, a cooler having refrigerant linesconnected thereto and valves for controlling the flow of refrigerantthrough said lines, a separate line also connected with the coolerhaving valves for controlling the flow of a warm fluid therethrough,means for circulating the medium to be cooled into contact with thecooler, a motor for operating said means, a switch controlled by theload on the motor due to a frosted condition of the cooler, said switchbeing in control of the valves for circulating refrigerant and forcirculating a warming fluid through the cooler, the warm fluid beingcirculated to remove the frost after the evaporator becomesobjectionably coated with frost, and a cut-out switch for stoppingcirculation of the warm fluid when the temperature of this fluid reachesa predetermined high degree, substantially as set forth.

6. A device for cooling air comprising a cooler, means for circulatingrefrigerant through the through the cooler, valve means in control ofsaid circulating means, a fan for circulating air over the cooler, amotor for operating said fan,

the load on said motor varying a result of the increase in the pressurehead through the cooler when the cooler becomes coated with ice orfrost, means controlled by variation in the load on the motor foroperating said valve means, a timing device for controlling operation ofthe said valvemeans, and means automatically operableupon the stoppingof circulation of refrigerant through the cooler for causing thecirculation of a warm fluid therethrough to hasten defrosting.

8. In combination, a cooler, means for circulating refrigerant throughthe cooler, means for circulating the fluid to be cooled over thecooler, a motor for driving said last-mentioned means, the load on themotor varying as a result of the restriction of the fluid path when thecooler becomes coated with ice or frost, means for causing circulationof warm fluid through the refrigerant path in said cooler to defrost thecooler, and means for controlling the circulation of said warm fluid inresponse to the variation of load on the motor.

9. In combination, a cooler, means for circulating refrigerant throughthe cooler, means for circulating the fluid to be cooled over thecooler, a motor for driving said last-mentioned means, the load on themotor varying as a result of the restriction of the fluid path when thecooler becomes coated with ice or frost, means for causing circulationof warm fluid through the refrigerant path in said cooler to defrost thecooler, means for controlling the circulation of said warm fluid inresponse to the variation of. load on the motor, and auxiliary controlmeans for preventing warm fluid above a predetermined temperature orpressure from circulating through the cooler.

WILLIAM R. KITZMILLER.

